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Forum Index : Electronics : Electrical Math, Argh!
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| gaspo Regular Member  Joined: 25/06/2018 Location: AustraliaPosts: 65 |
The other way to interpret scientific numbers is to prepend as many zeros in front of the number as the exponent indicates and then move the decimal point to be after the first zero. 1.61440e-4 = 0000161440 = 0.000161440, this is in Farad. You can then group digits after the zero into three to get milli, micro, nano, pico. 0.000 161 440 = 161.44uF Edited 2019-08-15 17:06 by gaspo |
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| Ironmaiden Regular Member Joined: 09/07/2019 Location: United StatesPosts: 53 |
Poida, Gaspo. A big thank you to both of you gentlemen. Honestly, We never covered scientific notation in high school. But then our education system these days are complete rubbish. I graduated in 2010 so am a victim of the indoctrination campuses that don't actually teach a thing except political agendas. Robert Edited 2019-08-16 01:12 by Ironmaiden |
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| Ironmaiden Regular Member Joined: 09/07/2019 Location: United StatesPosts: 53 |
Going on the data of page 38, I am getting a number greater for the delta connected capacitor bank. That can't be right though because a star connected capacitor bank requires up to 3 times the uf of a delta connected capacitor bank. 3 x 230 x 14= 9660VA Hence, Real power, 9660 x 0.87 = 8404W The reactive power can be obtained from the power triangle. (9660^2-8404^2) = 2268VAR Hence, The reactive power per phase, 2268/3 = 756VAR For delta connected capacitors, V phase = V line I phase = Q phase/ V phase = 756/230= 3.28A From equation 6, C = 3.28/(2pi x 60 x 230)=378uf 378uf being the total amount of capacitance needed means each of the three capacitors would need to be 126uf. That seems like a crazy amount for a 4KW induction generator. Surely that much UF would blow the windings out in a couple minutes. I've excited this generator with 3 50uf 440vac capacitors, as does most of the youtube videos on machines of 5.5kw up to 15kw. I'm thinking page 38 and 36 are reversed? Surely the 378uf is what would be needed for a star connected capacitor bank. The 161uf for a delta connected capacitor bank. Have I found a fatal flaw in Nigel's book??? Robert Edited 2019-08-16 02:48 by Ironmaiden |
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| Ironmaiden Regular Member Joined: 09/07/2019 Location: United StatesPosts: 53 |
While doing some research this evening I have come across an older book on induction generators written by Skat, A Swiss engineering firm in conjunction with German GATE a division of GTZ Gmbh. http://skat.ch/book/manual-on-induction-motors-used-as-generators-volume-10/ Robert Edited 2019-08-16 10:36 by Ironmaiden |
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